Hemianopia is the loss of one-half of a visual field (or one-quarter – quandrantopia). The patient is unaware of a visual stimulus presented in the affected field. This is different from visual neglect, when the patient would be aware of stimuli in each field tested individually, but not when tested simultaneously.
When hemianopia is present, it is not possible to comment of the presence of visual neglect.
Below is a simulation of hemianopia. Click on the grey buttons to show how damaging that nerve affects the visual field.
|The patient is able to see fingers moving in the left but not the right half of the visual field.|
|Here, the patient is aware of the fingers moving when tested in each field separately but neglects the field affected when both sets of fingers are moving.|